Smoking articles such as cigarettes are conventionally made by wrapping a column of tobacco in a white wrapping paper. At one end, the smoking article usually includes a filter through which the article is smoked. Filters are attached to smoking articles using a tipping paper which is glued to the white wrapping paper. The wrapping papers and tipping papers used to construct smoking articles are typically made from flax or other cellulosic fibers and contain a filler, such as calcium carbonate.
Besides being used to hold the cigarette together, cigarette wrapping papers and tipping papers also contribute to and control many physical properties and characteristics of the cigarette. For instance, cigarette wrapping paper affects the rate at which the cigarette burns, the number of puffs per cigarette and the total tar delivery per puff Another property of the cigarette that is affected by the wrapper is the appearance and the characteristics of the ash that is formed as the cigarette burns. cigarette paper can even be used to limit the amount of smoke that emanates from the lit end of a cigarette when it is left burning and to reduce the tendency of a cigarette to ignite adjacent surfaces.
In addition to performing the above described functions, cigarette wrapping papers must also provide the cigarette with an overall aesthetic appearance. For instance, cigarette wrapping papers, which are mostly white, should have as bright a color as possible. Also, the paper should have a very high opacity. By having a high opacity, the wrapping paper masks the contents of the cigarette.
In the past, wrapping paper opacity was determined primarily as a function of the amount of filler incorporated into the papers. In general, opacity levels are increased as the amount of filler added to the paper is increased. Unfortunately, however, increasing filler levels to increase opacity can adversely effect other characteristics of the paper. For example, increasing filler levels can decrease the strength of the paper. Altering filler levels can also affect the permeability of the paper which may in turn affect the burn properties of the paper. As such, there is increasing pressure within the industry to keep filler levels in cigarette paper within preset ranges, severely restricting viable methods for increasing paper opacity.
Besides increasing filler levels, the opacity of cigarette paper can also be somewhat changed by changing the amount that the fiber furnish is refined and by altering the composition of the fiber furnish. Changing the fiber furnish or the amount that it is refined, however, may also adversely interfere with other physical characteristics of the paper. Further, varying refinement or selecting a different fiber furnish only provides small increases in opacity.
Due to the above limitations, commercial cigarette wrappers containing calcium carbonate as the filler generally only have an opacity of from about 74% to about 76% In the past, it has been extremely difficult to create a commercially acceptable paper wrapper having an opacity of 80% or above.
Thus, a need exists for a wrapping paper for smoking articles that has a high opacity, such as greater than 80%. Also, a need exists for a method of producing such wrappers. A need also exists for a method of increasing the opacity of cigarette wrapping papers without adversely interfering with other physical properties of the paper. A need further exists for a method for increasing the opacity of cigarette papers without having to increase filler levels.